Furnace and its method of operation



April 27, 1937.

K. M. SIMPSON FURNACE AND ITS METHOD OF OPFRATION Filed Feb. 21, 1936Gum} JYemmi/l Jim s01:

Patented Apr. 27, 11937 UNITED STATES PATENT OFFICE 9 Claims.

-My invention relates to furnaces and their method of operation and moreparticularly has reference to improvements in the heating process of myprior Patent No. 1,812,563, June 30, 1931, said process having specialutility in the art of metallurgy for the production of steel, iron, ferro-chrome and other metals and alloys.

In my prior patent referred to, I have disclosed and claimed a heatingprocess wherein the charging material on the hearth is heated by flameimpingement against the surface thereof, the flames being generated bymeans of burners mounted in the furnace roof or arch and being directeddownwardly onto the charge under high a velocity. According to thespecific operation illu'strated in the patent, the total air forcombustion of the fuel is supplied with the latter through the furnaceroof. This presents somewhat of a problem in large furnaces and alwaysinvolves considerable expense in the installation of the large pipes orconduits necessary to carry the large volumes of air required forcombustion of the fuel over the top of the furnaceand through theburnerblocks.

It is a principal object of the present invention to simplify and reducethe cost of the installation for supplying the air to top firedfurnaces, such as illustrated in my prior patent referred to.

According to the present invention, the air required for combustion ofthe fuel is supplied in part with the fuel through the furnace roof andin part through ports in an end of the furnace. Thatis to say, the totalcombustion supporting inedium is divided between the fuel supply means'and an end wall of the furnace, a portion thereof being projecteddownwardly into the furnace with the fuel and the remaining portionthereof being passed in a generally horizontal direction 40 through thefurnace. For greatest simplification of the apparatus, the airintroduced through the endwall of the furnace constitutes the majorportion of the combustion supporting medium while only, a minor portionthereof is supplied through the furnace roof with the fuel. For example,in the case of oil firing, 90% of the air for combustion purposes may beintroduced through ports in the ends of the furnace and the remaining10% supplied with the fuel through the burner blocks in the furnaceroof. These proportions are, of course, quite variable according to thetype of burner, the viscosity of the oil, the temperature at which it isintroduced to the furnace and other factors.

The invention is of, special utility in the use of liquid fuel or oilsince when burning gaseous fuel, it is not necessary to introduce any ofthe air required for combustion through the roof. However, in the caseof gaseous fuel, it may be desirable in some instances to introduce apor tion of the total combustion air with the fuel through the burnerblocks or ports in the roof. For more detailed understanding of theinvention, reference willbe had to the accompanying drawing, wherein YFigure 1 is a plan'view of an apparatus capable of carrying outtheprocess and Figure v2 is a sectional view on the line 22 of Figure 1and showing the charge in melted form. Referring more particularly tothe drawing, at I is shown a furnace of the open hearthtype, having theusual hearth 2 and arched roof 3. An air inlet conduit 4 and a dischargeconduit 5 for combustion products are provided at opposite ends of thefurnace. The air supplied to conduit 4 may be preheated in a recuperatoror regenerator in the customary manner and the arrangement is such as topermit the alternate introduction of air to and discharge of combustionproducts from each end of the furnace as in the usual open hearthfurnace operation.

An oil supply manifold 6, over the top of'the furnace, communicatesthrough branches 1 with each of the fuel inlet pipes 8 projectingthrough arch 3 into the furnace and terminating in orifices or nozzles9. Each fuel pipe 8 is provided witha valve IO for independentlycontrolling the fuel supply to the several orifices. The fuelinlet pipesare spaced throughout the furnace roof in sufiicient number to cover thecharge on the hearth with flame, as in my prior patent above referredto.

Above the furnace, on opposite sides thereof, are air manifolds I Ihaving branches I2 leading to pipes I3 surrounding the fuel pipes B forsupplying additional air to the furnace in admixture with the fuel. Eachof the branch lines I2 is provided with an independently operable valveI4 for controlling the quantity of additional air admitted to thefurnace through each of the pipes I3.

The material to be heated is supplied to the furnace through opening l5having closure l6 and the molten material is discharged from the furnacethrough outlet II.

In operation, a charge of the material to be heated having been placedupon the hearth, the major quantity of the air required to supportcombustion, say 90%, is introduced to the furnace through conduit 4 in ahorizontal or slightly downward direction and is caused to travelthrough the furnace in a generally horizontal plane. At the same time,oil and the minor portion of the air for combustion thereof areintroduced through the furnace roof by the means already described, thestreams of admixed fuel and air being projected downwardly withsufficient pressure to penetrate the moving stream of air and combustionproducts and to forcibly impinge upon the charge. The fuel is burnedwhile thus impinging against the surface of the material undergoingheating and preferably the entire charge is blanketed with flame, thusgenerated near the surface thereof.

From the foregoing it will be seen that by introducing the majorquantity of the air required for combustion through an end or ends ofthe furnace, the greater part of the overhead air supply means shown inmy prior patent referred to is eliminated while still obtaining all theadvantages of the patented process.

Having thus described my invention, I claim:

1. In the operation of open hearth furnaces, the method which comprisescharging the material to be treated onto the furnace hearth, introducingsubstantially all of the fuel required for the operation of the furnaceto the upper portion of the furnace above the hearth and projecting thesame downwardly toward the hearth, burning thefuel with air adjacent thematerial on the hearth, introducing a portion of the air to the upperportion of the furnace with the fuel and simultaneously introducinganother portion thereof through a side of the furnace to flow in asubstantially horizontal direction through the furnace over the materialon the hearth.

2. A method for operating furnaces which comprises introducingsubstantially all of the fuel required for the operation of the furnacethrough the furnace roof and projecting the same downwardly toward thefurnace floor, burning the fuel in the furnace, introducing the majorquantity of air required for combustion of the fuel through a side ofthe furnace in a generally horizontal direction, and simultaneouslyintroducing a minor proportion of the air through the furnace roof withthe fuel to be projected downwardly therewith.

3. In a heating method of the character wherein the material to beheated is placed on a furnace hearth and blanketed with flame, theimprovement which comprises introducing admixed fuel and air to theupper portion of the furnace and projecting the same downwardly in aplurality of streams toward the material on the hearth, andsimultaneously introducing additional air substantially free of fuelthrough a side of the furnace in a generally horizontal direction.

4. A heating method which comprises charging the material to be heatedon a furnace hearth and covering the major portion of the surface of thecharge with flame, introducing substantially all of the fuel requiredfor the generation of said flame to the furnace at a plurality of spacedpoints above the hearth and directing the same in streams downwardlytoward the material on the hearth, supplying the major portion of theair required for combustion of the fuel through a side of the furnace,and simultaneously supplying the remaining portion of the air with saiddownwardly directed streams of fuel.

5. In the operation of top-fired open hearth furnaces wherein the fuelis projected downwardly toward the furnace hearth, the improvement whichcomprises passing the major portion of the air required for combustionof the fuel through the furnace in a generally horizontal direction, andsimultaneously supplying the revmaining portion of the air to thefurnace in admixture with the downwardly projected fuel, said majorportion of the air being introduced to the furnace unadmixed with fueland the total fuel for the furnace operation being introduced with saidremaining portion of the air.

6. In the operation of open hearth furnaces, the method which comprisesprojecting a plurality of streams of admixed oil and airdownwardly fromthe upper portion of the furnace toward the furnace hearth, the quantityof air so admixed with the oil being only a minor portion of the airrequired for combustion of the oil, and simultaneously passing theremaining portion of air necessary for the combustion of the oil intothe furnace unadmixed with fuel and in a generally horizontal direction.

'7. In the operation of oil fired furnaces wherein the oil is projecteddownwardly from the upper portion of the furnace toward the furnacehearth, the method which comprises supplying the major portion of theair required for combustion of the oil through an end of the furnace ina generally horizontal direction, and simultaneously introducing theremaining portion of the air in admixture with the downwardly projected011, said major portion of the air being introduced to the furnacesubstantially free of fuel.

8. A heating process which comprises placing a charge of the material tobe heated on the hearth of a furnace, introducing oil through thefurnace roof above the hearth in suflicient quantity to supplysubstantially all of the heat for the furnace operation and directingthe same downwardly under pressure against the charge, burning the oilwhile impinging on the charge, introducing the major portion of the airrequired for combustion of the oil to the furnace in a substantiallyhorizontal direction, and simultaneously supplying the remaining portionof the air to the furnace in admixture with the oil.

9. A heating process which comprises placing a charge of the material tobe heated on the hearth of a furnace, supplying oil in a plurality ofstreams projected downwardly from the roof of the furnace toward thehearth, the amount of oil so introduced being sufficient to blanket thecharge with flame, introducing the major portion of the air required forcombustion of the oil through an end wall of the furnace in a generallyhorizontal direction, and simultaneously supplying the remaining portionof the air through the furnace roof together with said oil streams.

KENNETH M. SIMPSON.

